1. Field of the Invention
The present invention relates to a brake hydraulic pressure control apparatus for a vehicle such as motorcycle or four-wheel vehicle.
2. Discussion of the Related Art:
Heretofore, as one type of brake hydraulic pressure control apparatuses for vehicle, there has been known one which is described in United States Patent Application Publication No. US 2007/0069577 A1 (equivalent of JP 2007-91051 A). In the known system, a hydraulic pump is held to be driven throughout an ABS control, in which during a pressure reduction control, a pressure increase valve is closed and a pressure reduction valve is opened, whereas during a pressure increase control, the pressure reduction valve is closed and the pressure increase valve is regulated to attain a desired pressure increase rate, whereby a wheel cylinder pressure is varied to control the braking force. More specifically, the differential pressure between a master cylinder pressure (M/C pressure) and a wheel cylinder pressure (W/C pressure) during the ABS control is appropriately inferred, and the pressure increase valve under a pressure increase control is regulated to attain a differential pressure inference value. The differential pressure inference value is obtained from the difference between a wheel cylinder pressure inference initial value (Pw0) and a wheel cylinder inference value (Pw) with consideration for a wheel cylinder pressure (Pg) that causes a wheel to lock. Further, during the ABS control, the hydraulic pump remains being driven from the beginning of the ABS control to the termination of the same.